This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


[Xen-tools] RE: [Xen-devel] Hi,something about the xentrace tool

To: "Rob Gardner" <rob.gardner@xxxxxx>, "NAHieu" <nahieu@xxxxxxxxx>
Subject: [Xen-tools] RE: [Xen-devel] Hi,something about the xentrace tool
From: "Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>
Date: Thu, 15 Jun 2006 08:06:11 +0100
Cc: xen-tools@xxxxxxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx, rickey berkeley <rickey.berkeley@xxxxxxxxx>, xen-users@xxxxxxxxxxxxxxxxxxx
Delivery-date: Thu, 15 Jun 2006 00:06:26 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
List-help: <mailto:xen-tools-request@lists.xensource.com?subject=help>
List-id: Xen control tools developers <xen-tools.lists.xensource.com>
List-post: <mailto:xen-tools@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-tools>, <mailto:xen-tools-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-tools>, <mailto:xen-tools-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-tools-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AcaPzMCsIz1gvXxeTAmjGAc1UaXZIQABOwmQ
Thread-topic: [Xen-devel] Hi,something about the xentrace tool
> If overflow occurs, it is not handled. The mechanism I implemented was
> just designed to drastically reduce the probability of overflow.

It does count the number of lost trace messages and add a trace message
to that effect though, right?


> Currently, the trace buffer "high water" mark is set to 50%. That is,
> when the hypervisor trace buffer becomes 1/2 full, it sends a soft
> interrupt to wake up xenbaked from its blocking select(). If nobody
> wakes up to read trace records from the trace buffer, I take that to
> mean that nobody cares about the trace records. When somebody does
> they will read those records in a timely manner. Obviously, the
> hypervisor cannot "block" if there is no room in the trace buffers; In
> this case, new trace records simply overwrite old ones, and the old
> are lost.
> If you encounter a situation where trace records are being generated
> fast, and fill up the trace buffer too quickly, then the simple next
> step is to increase the size of the trace buffers. So far, use of the
> trace records has not been linked to anything so critical that it's
> necessary to take extraordinary measures to avoid loss of data.
> Rob
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel

Xen-tools mailing list